1. Field of the Invention
This invention is concerned with improvements in or relating to area measuring machines.
2. Prior Art
In the complete specification of U.S. Pat. No. 3,717,414, issued Feb. 20, 1973 U.K. Pat. No. 1,446,866, are described area measuring machines comprising (a) support means, e.g., a roller, for supporting sheet material the area of which is to be measured and for feeding the material through the machine, (b) a plurality of wheels disposed side by side across the machine and arranged to run on the roller or on sheet material fed by the roller past the wheels, (c) detecting means, one associated with each wheel, for detecting the presence of a piece of sheet material fed between the wheel and the roller, (d) signalling means for signalling each time the periphery of a wheel has been rotated through a unit distance by the passage of sheet material therepast and (e) computing means for summing the signals from each wheel to indicate the area of the piece of sheet material.
Such machines have been found to be, in operation, reliable and accurate. However, should a fault develop on a machine such as described in the aforementioned patent specifications, it is difficult to notice. In order to test that such machines are operating satisfactorily it is a known practice to feed a piece of leather of known area through the machine a number of times, and check that the area of the piece registered by the machine is within the permitted tolerances.
One of the various objects of the present invention is to provide an improved area measuring machine in which it is possible readily to check that the machine is operating satisfactorily.